<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
{% block header %}
    <h1>顶部</h1>
{% endblock %}

{% block main %}
    <h1>中间</h1>
{% endblock %}

{% block footer %}
    <h1>底部</h1>
{% endblock %}
</body>
</html>